Post hole digger accessory for tractors



May 12, 1964 McGEE POST HOLE DIGGER ACCESSORY FOR TRACTORS 5 Sheets-Sheet 1 Filed Sept. 19, 1960 5 @i} l e/anj 2 52; 254w 35 A/farnfl May 12, 1964 L. T. M GEE POST HOLE! DIGGER ACCESSORY FOR TRACTORS 3 Sheets-Sheet 2 Filed Sept. 19, 1960 May 12, 1964 McGEE 3,132,705

POST HOLE DIGGER ACCESSORY FOR TRACTORS Filed Sept 19, 1960 3 sheets-sheet 3 United States Patent 3,132,705 POST HULE BIGGER ACCESSGRY FGR TRACTORS Leland T. McGee, 410 Dixon Ave, Compton, Calif. Filed ept. 19, 19643, Ser. No. 56,917 4 Claims. (Cl. 173-160) This invention relates to a post hole digger and, more particularly, a post hole digger of the auger type that is mounted on a tractor with the auger connected to the tractor power takeoff.

A post hole digger of this type is mounted on a boom and operates with gravity feed. In other words, the force that urges the rotating auger into the ground is only the weight of the auger unit with whatever added weight may be imposed by the boom. There has been a long standing need for increasing the efficiency of such a power driven digger not only for increasing the number of post holes that may be dug in an hour in ordinary soil but also to make the device capable of digging holes economically in harder, more compact soil into which a conventional post hole digger can hardly penetrate. The present invention teaches that this need may be met by providing power means to apply high magnitude downward swinging force to the boom that carries the auger.

The invention is in the manner in which this downward force is created and applied to the boom and in the manner in which a relatively simple kit makes it possible to convert a conventional tractor-mounted gravity-feed auger into a power feed auger. The present disclosure is directed primarily to such a conversion kit but it is to be understood that the invention may also be incorporated in the factory construction of a tractor-mounted post hole digger.

The invention takes advantage of well-known facts which have not been heretofore appreciated as making possible the power feed of a ground boring anger at such low initial cost that the cost may be quickly absorbed by increased production. One of these facts is that although a conventional tractor is not adapted to power the downward movement of the post hole digger boom, nevertheless the tractor has a hydraulic power system that can supply the required force. A second fact is that while a conventional boom is not strong enough and rugged enough to be used for transmitting a high magnitude driving force to the auger at the end of the boom, it is a simple matter to make the boom strong enough once the idea is conceived of using the boom for the purpose.

A feature of the invention is the manner in which it converts the conventional boom-lifting mechanism to the new purpose of also powering the downward movement of the boom. This conversion is accomplished by the simple expedient of substituting a power lever for a pair of lift links in the usual lift mechanism. The power lever of the invention that is substituted for the left links connects the draw bar links to the boom in substantially the same manner as the replaced lift links but is of more rugged construction and has an upwardly extending portion or arm for connection to a hydraulic power means.

The kit includes a hydraulic power cylinder for operating the power lever, a valve for controlling the power cylinder, means to reinforce the conventional boom, which means provides a connection for the power cylinder, and finally the new rugged power lever. It is a simple matter to weld the reinforcing structure to the boom, to substitute the new power lever for the usual lift links, and to connect the power cylinder to the hydraulic cylinder of the tractor.

The features and advantages of the invention may be understood from the following description together with the accompanying drawings. a

In the drawings, which are to be regarded as merely illustrative FIG. 1 is a perspective view of the presently preferred embodiment of the invention installed on the rear of a conventional tractor;

FIG. 2 is a fragmentary plan view showing the boom and associated mechanism;

FIG. 3 is a fragmentary side elevation of the boom and associated mechanism;

FIG. 4 is'a diagrammatic view of the boom and the associated power lever showing how power actuation of the lever urges the boom downward;

FIG. 5 is a front elevation of the power lever that replaces the conventional lift links;

FIG. 6 is a perspective view of a blocking member which may be included in the kit to prevent yielding action on the part of the yielding means for connecting the boom with the tractor;

FIG. 7 is a perspective View showing how the blocking member shown in FIG. 6 is mounted on the tractor near the end of the boom;

FIG. 8 is a fragmentary side elevation of the tractor with parts broken away to show the relationship between the added blocking member and the associated mechanism of the tractor; and

FIG. 9 is a fragmentary side elevational view of a portion of the structure shown in FIG. 7.

FIG. 1 shows a conventional tractor on which a conventional boom, generally designated B, is pivotally mounted to swing in an upright plane. The boom B comprises a pair of longitudinal tubular frame members 10 strengthened on their undersides by reinforcements 11. The tubular frame members 10 converge and are connected to the tractor by a universal joint 12 comprising a ball member embraced by a bearing and which is mounted on a fixed tractor bracket 14 and which not only permits the boom to swing up and down relative to the tractor but also permits the boom to tilt about its longitudinal axis relative to the tractor when the terrain tilts the tractor laterally.

The tractor has the usual pair of draw bar links 15 which are connected by corresponding tension links 16 and 16a to a pair of power-actuated tractor arms 18.

The draw bar links 15 may, for the purpose of the present application, be aptly termed lift arms since their sole function in the operation of a conventional tractormounted post hole digger is to lift the boom B. For this purpose, the outer ends of the lift arms 15 are operatively connected to the boom B in a well-known manner by a corresponding pair of lift links that are not shown in the drawings.

The tension link 16a is adapted in a Well-known manner for extension and contraction in length by screw action and for this purpose is made in two sections as shown. A manually operable crank 19 controls the effective length i of the tension link 16a and may be manipulated to rock l which extends downward from a gear case 22. The gear case has a pair of upwardly extending ears 24 for pivotal connection to the boom B. For this purpose, the cars 24 are apertured to receive a transverse pivot pin 25 which is mounted in the outer ends of the two frame members 10 of the boom. e

The auger 20 is driven by a power take-off from the tractor. In the construction shown, a drive shaft section 26 extends from the gearcase 22 towards the tractor and is supported by a fixed bracket 28 on the exterior of the gear case. The drive shaft section 26 is connected by a universal joint 30 to a second tubular drive shaft section 32. ,The tubular drive shaft section 32 telescopes over a third drive shaft section 34 and is splined thereto, the third drive shaft section being powered by the tractor.

Usually means is provided to swing the suspended auger unit forward or rearward relative to the boom whenever desired. For this purpose, an upwardly extending arm in the form of a triangular plate 35 is rigidly mounted on the gear case 22 and this arm is connected by a push-pull rod 36 to a manual control lever 38.

The structure described to this point is conventional and not part of the present invention. For an understanding of the present invention, it is important to note that in the conventional post hole digger the lift arms 15 are never used to urge the boom downward, the boom merely being released to gravitate whenever downward movement is required. When the auger is actuated to bore a post hole, the two lift arms 15 are merely relaxed to permit the weight of the boom to be transferred to the auger.

The embodiment of the invention shown in the drawings comprises structure in kit form to be added to the described conventional structure. The kit includes means to reinforce the boom B to strengthen the boom for the purpose of the present invention since the conventional boom B is no stronger than is necessary to lift the auger unit. For the purpose of the present invention, the boom must be capable of exerting downward force of relatively high magnitude to drive the auger 2t downward into the soil at a much greater rate than would be possible if the auger were fed solely by gravity.

The means for reinforcing the boom may comprise a pair of heavy flat bars 4i that areshaped and dimensioned to rest on the top surfaces respectively of the tubular frame members 10. The two flat bars 49 are bent to converge as best shown in FIG. 2, the bent ends being welded to a bracket that comprises a pair of upright ears 42 interconnected by a short cross bar 44 [FIG. 3}. It is contemplated that the two bent heavy fiat bars 46 will be welded in advance to the upright ears 4% and cross bar 44*. In other words, in the preferred practice of the invention, the two heavy flat bars as are welded to the upright ears 42 and the cross bar 44 before the kit is sold. in installing the kit, the heavy fiat bars 48 are welded at numerous points to the upper surfaces of the tubular frame members iii, the welds being indicated by numerals 45.

included in the kit is a special A frame or A-shaped power lever, generally designated L. This power lever is of exceptionally heavy construction, being much stronger than the lift links that it replaces since the lever is subjected to bending stress for applying high magnitude downward force to the boom B. As may be seen in FIG. 5, the power lever L comprises a pair of divergent down- Wardly extending arms 48 in the form of channel members, the lower ends of the arms having integral trunnions 49 for pivotal connection to the lift arms 15. The two arms 48 are interconnected by a transverse tube 59. The tube So is provided with reinforcement bushings 52 in its opposite ends and is adapted to be mounted on the boom 13 by a transverse pivot pin 54. The pivot pin 54 extends through the tube 50 and through corresponding apertures in the boom B. In the construction shown, the apertures for the pivot pin 54 are in the two lower reinforcement bars 11, as may be seen in FIG. 1.

The lever L has a portion or arm means which extends above its fulcrum. As may be seen in FIG. 5, this upwardly extending portion includes a pair of ears 55 to pivot the previously mentioned manual lever 38 and further includes an upper central pair of ears 56 for connection to power means for actuating the lever.

In the construction shown, the two cars 56 are connected by pivot means 57 to a piston rod 58. The piston rod 58 is connected to a piston [not shown] in a hydraulic power cylinder en. The opposite end of the hydraulic cylinder 6% has a rigid extension in the form of a rod 62 which is connected by a pivot pin 64 to the previously mentioned upright ears 42 of the reinforced boom. It is contemplated that the headed pivot pin 64 will be quickly removable and for this purpose, the pivot pin is releasably retained by a retaining pin 65 that is equipped as shown with a small ring for use as a handle. As shown .tached by the same yielding pivotal connection.

4- in FIG. 1, the power cylinder of is connected to a fourway control valve 66 by a pair of hoses 68 and the control valve is connected by suitable means [not shown] to the hydraulic system of the tractor.

The manner in which the invention serves its purpose may be readily understood from the foregoing description. The boom B may be elevated when desired in the usual maner by the hydraulic system of the tractor acting on the two lift arms 13, the lever L serving the function of the usual lift links in transmitting the lifting force to the boom.

The manner in which the hydraulic power cylinder 60 operates to swing the boom downward may be understood by referring to the simplified diagrammatic view in FIG. 4. FIG. 4 shows the boom at a position to which it has been elevated by the lift arms 5. It is apparent that if the valves in the hydraulic system on the tractor are opened to free the two left arms 18 for motion and if the hydraulic power cylinder 6% is actuated to retract the piston rod 62 and thereby rotate the lever L clockwise, the boom will be forced downward as indicated by the dotted line positions of the parts. Thus, the invention em ploys the power lever L not only as a lift link in the usual manner, 'but also as a power means for swinging the.

boom downward. It is also apparent that the invention gives a new function to the lift arms 15 since the lift arms serve as tension links in the power-actuated downward movement of the boom.

It may be readily appreciated that the boom and the associated mechanism may be readily removed to permit the tractor to be used for other operations. It is a simple matter to disconnect the lever L from the lift arms 18 and to disconnect the boom from the tractor. It is also a simple matter to disconnect the power cylinder 69 from the hydraulic system of the tractor. An advantage of the invention is that the power cylinder of may be used with implements other than the auger unit.

in some tractors the compression link that is replaced by the boom has a yielding connection with the tractor and whenever this yielding connection is unduly stressed by an unusual magnitude of reaction force, a ram cylinder is automatically energized to exert lifting force on the compression link. Thus, whenever an implement, such as a plow carried by the tractor, tends to dig too deeply into the soil, the consequent increased resistance to forward movement of the implement causes a reaction force to be exerted across the yielding connection whereupon the ram cylinder responds by exerting lifting force on the implement.

When a boom is substituted for the compression link for the purpose of the present invention, the boom is at Unfortunately, under some conditions that arise in the boring of a hole in the soil a reaction force may be created which acts on the yielding connection and causes the ram cylinder by its lifting action to oppose the downward action of the power cylinder 66 of the present invention. T o solve this problem the accessory kit may include means to limit the stressing of the yieidabie connection of the boom with the tractor.

This aspect of the invention may be understood by referring to FIGS. 6-9. FIG. 8 shows how the usual lift arms 1's" are connected by the usual tension iinks 16 to corresponding power actuating tractor arms 13 mounted on a lift shaft iii. A ram cylinder 72 for actuating the lift shaft 7i) has a piston 74 connected to a rocker arm 75 that is. keyed to the lift shaft. The operation of the ram cylinder 72 is controlled bye. valve '76. FIG. 8 shows an inclined compression link 78 which is a conventional part of the tractor mechanism but which is replaced by the previously described boom for digging post holes. The compression link 73 or the boom of the present invention that replaces the compression link is connected by a pivot 89 to a pivoted bracket 82, the. bracket bein mounted on the tractor by a pivot 84. It p is apparent that any forward reaction force on the part of the compression link or the boom that replaces the compression link will tend to rock the bracket 82 forward or clockwise.

The bracket 82 is connected by a pivot 85 to a push rod 86 and the push rod in turn is connected by a link 88 to a pivot 90 on an upright lever 92. The push rod 86 is made in two telescoping sections to permit limited extension and contraction. A coil spring 94 that surrounds the push rod seats against a flange 95 of one of the push rod sections and seats against a fixed bracket 96 to resist contraction of the push rod. When the push rod is contracted to its maximum, it exerts force on the upright lever 92 to cause the upright lever to operate the valve 76 for energizing the ram cylinder 72. The upper arm of the upright lever 92 above the pivot 90 abuts a stop 98 and the lever is biased against the stop by a coil spring 100. The lower end of the upright lever has a pivotal connection 102 with the valve 76.

The kit of the present invention includes a blocking member 104 which may be interposed between the pivoted bracket 82 and the fixed bracket 96 to prevent sufiicient contraction of the push rod 86 to cause the undesirable operation of the valve 76. The blocking member 104 comprises a metal bar 105 with a rectangular plate 104 welded to one end of the bar and with a smaller plate 108 welded to the other end of the bar. The rectangular plate 106 has a pair of screw holes 110 and the small plate 108 is shaped to form an end tongue 112 flanked by a pair of lateral shoulders 114.

As shown in FIG. 8, a U-shaped spring 116 for supporting the tractor seat 118 is mounted on the tractor housing by a pair of cap screws 120. The rectangular plate 106 of the blocking member 104 is inserted under the U-shaped spring 115 and is anchored by the two cap screws 120, the end of the bar 105 of the blocking member being positioned adjacent the fixed bracket 96. At the opposite end of the blocking member 104 the end tongue 112 is inserted under the lower edge of a transverse web 122 of the pivoted bracket 82 with the lateral shoulders 114 in abutment against adjacent portions of the pivoted bracket.

It is apparent that the blocking member 104 may be quickly installed without difliculty and without requiring any special tools. It is also apparent that the blocking member will prevent effective longitudinal contraction of the push rod 86 and will thereby prevent operation of the valve 76.

My description in specific detail of the selected embodiment of the invention will suggest various changes, s ubstitutions and other departures from my disclosure within the spirit and scope of the appended claims.

'I claim:

1. In a post hole digger wherein a boom is mounted on a tractor to swing in a vertical plane and a power-driven auger is pivotally suspended from the outer end of the boom, power means to force said auger axially into the ground, said power means comprising:

lever means pivotally mounted on said boom for rotation relative to the boom in a vertical plane, said lever means having downwardly extending arm means; lift arm Inc-ans below the boom and extending longitudinally thereof from the tractor, said lift arm means being connected to said downwardly extending arm means of the lever means to lift the boom, said lift arm means being releasable for free movement; and power means operatively connected to said lever means to rotate the lever means relative to the boom to swing said downwardly extending arm means thereof in the direction away from the tractor thereby to exert force to swing said boom downward to urge the auger axially downward.

2. A combination as set forth in claim 1 in which said lever means has an arm portion extending upward from its pivot; and in which said power means is operatively connected to said arm portion to pull the arm portion towards the tractor thereby to exert force to swing said boom downward to urge the auger axially downward.

3. A combination as set forth in claim 2 in which said power means interconnects said arm portion of the lever and said boom.

4. A mobile post hole digger, comprising: a tractor; a boom pivotally mounted on said tractor; an earth-boring auger pivotally suspended from the outer end of the boom; a pair of lift arms extending outward from the tractor under the boom; lever means pivotally mounted on said boom and extending downward therefrom, said lever means being connected to said lift arms; power means on the tractor to lift said lift arms thereby to transmit force to the boom through said lever means to lift the boom, said lift arms being releasable from the power means for freedom of movement; and fluid-pressure-actuated power means operatively connected to said lever means to rotate said lever means relative to the boom in the direction to place said lift arms under tension while the lift arms are released thereby to exert downward swinging force on the boom to force said auger axially downward to facilitate the penetration of the auger into the soil.

References Cited in the file of this patent UNITED STATES PATENTS 2,414,072 Taft Ian. 7, 1947 2,543,282 Folken Feb. 27, 1951 2,557,637 Danuser June 19, 1951 2,581,535 Jackson Jan. 8, 1952 2,730,330 Ball Jan. 10, 1956 2,960,172 Henson Nov. 15, 1960 

1. IN A POST HOLE DIGGER WHEREIN A BOOM IS MOUNTED ON A TRACTOR TO SWING IN A VERTICAL PLANE AND A POWER-DRIVEN AUGER IS PIVOTALLY SUSPENDED FROM THE OUTER END OF THE BOOM, POWER MEANS TO FORCE SAID AUGER AXIALLY INTO THE GROUND, SAID POWER MEANS COMPRISING: LEVER MEANS PIVOTALLY MOUNTED ON SAID BOOM FOR ROTATION RELATIVE TO THE BOOM IN A VERTICAL PLANE, SAID LEVER MEANS HAVING DOWNWARDLY EXTENDING ARM MEANS; LIFT ARM MEANS BELOW THE BOOM AND EXTENDING LONGITUDINALLY THEREOF FROM THE TRACTOR, SAID LIFT ARM MEANS BEING CONNECTED TO SAID DOWNWARDLY EXTENDING ARM MEANS OF THE LEVER MEANS TO LIFT THE BOOM, SAID LIFT ARM MEANS BEING RELEASABLE FOR FREE MOVEMENT; AND POWER MEANS OPERATIVELY CONNECTED TO SAID LEVER MEANS TO ROTATE THE LEVER MEANS RELATIVE TO THE BOOM TO SWING SAID DOWNWARDLY EXTENDING ARM MEANS THEREOF IN THE DIRECTION AWAY FROM THE TRACTOR THEREBY TO EXERT FORCE TO SWING SAID BOOM DOWNWARD TO URGE THE AUGER AXIALLY DOWNWARD. 